Rihanna gets a little risque in new Dior 'Secret Garden' photos

Rihanna is never afraid to show a little leg ... or thigh ... or butt ... or nipple, so her much-hyped Dior campaign is actually a bit tame compared to what we've come to expect on her Instagram ... except for one pic.

Yep -- this one, where she seems eager to pop that boob right on out!

Like we haven't seen those a million times before...

Girlfriend does look banging though, of course.

And, we'll take one each of those bags and the sunglasses, Kthxbye.